Niall Iain Macdonald and Calum Macaulay take to the water as they explore the Forth and Clyde Canal. They take the tiller of their own barge, the Lochan Ora, and navigate their way across central Scotland. Niall Iain meets Ruaridh Graham of Historic Scotland to learn about the Antonine Wall - built by the Romans 2,000 years ago, it sits alongside much of the canal.